Recently I was rerouting a tube for my cold air intake and it got crushed without me knowing. The car started ok and went very slow ok, but would bog down from lack of air if I tried to accelerate. One time I tried to accelerate from a stop and I heard 3 loud knocks from the engine unlike anything I'd ever heard before. I stopped and limped slowly home. After I fixed the problem it ran fine. The car is an 89 Firebird w/305 ci and tpi. My question is how does running so rich cause a knock in the engine? Is it produced differently than the usual knocks and pings? Thank you.

 

Running rich won't cause knock. The knock was caused by something else or it wasn't spark knock at all. I can't think of anything though.

 

Thanks Slim, seems I've got a bit of a puzzle here. It didn't sound good at all, but at least it hasn't happened any more.

 

An extreme case would be if your fuel failed to vapourize and formed droplets in your combustion chamber. If you get enough fuel remaining in liquid form you can raise the dynamic compression ratio enough to force detonation.

 

I realize that liquids are relatively incompressable compared to gases, but if the fuel all remained in liquid form shouldn't it take up less space than if it vaporized properly? Therefore, there should be lower compression, right? It should be harder to ignite too. Is there some reason to expect more fuel to be injected if the air volume is low?

 

vapourized fuel takes up the same space as the air it's taking.
liquid fuel takes up space seperate to the air charge. If the fuel is in a liquid state it will raise the dynamic compression in the cylinder.

a constricted air intake shouldn't cause your fuel system to dump large amounts of fuel into the motor. especially a computer controled system.

do you have a manual tranny? If you do I'll bet when you bogged it off the line you lugged the motor enough to cause bearing knock.

no biggy

 

It's an automatic. Umm, what's bearing knock?

 

I should say, bearing rattle
in a manual if your lug the motor badly (4th gear at 10mph) the engine will be trying to drive the car at like 500rpm.. the strain on the engine at such a slow rpm induces disturbing sights and sounds, such as a rattling sounds, knocking sounds sometimes and lots of shaking etc. assuming the you don't stall the motor first

 

Ok, I understand now, thanks.